The present invention relates to a magnetic head for a perpendicular recording system and a fabrication process thereof.
A magnetic recording system has a magnetic recording medium and a magnetic head, and data in the magnetic recording medium are read/written by using a magnetic head. It is necessary to reduce a recorded bit for improving the recording capacity per unit area of the magnetic recording medium. However, in a current longitudinal recording system, there is the problem that the recording density cannot be improved because of a thermal fluctuation of magnetization of the medium when the recorded bit length becomes smaller. As a solution of this problem, there is a perpendicular recording system, in which the magnetization signal is recorded along the perpendicular direction in the medium. There are two kinds of methods in a perpendicular recording system. One is a method in which a double-layered perpendicular medium has a soft under layer as the recording medium, and another is a method in which a single-layered perpendicular medium has no soft under layer. In the case when the double-layered perpendicular medium is used as the recording medium, larger write-field intensity can be applied by using a so-called single-pole-type writer which has a main pole and an auxiliary pole.
FIG. 19 is a schematic drawing illustrating a relationship between a perpendicular magnetic recording head 14 and a magnetic disk 11 and perpendicular recording. The magnetic field generated from a main pole 1 of a write head 25 passes through a magnetic recording layer 19 and a soft under layer 20 of the magnetic disk medium 11, forms a magnetic circuit entering an auxiliary pole 3, and records a magnetization pattern in a magnetic recording layer 19. There is a case in which an intermediate layer is formed between the magnetic recording layer 19 and the soft under layer 20. A giant magneto resistive element (GMR) or a tunneling magneto resistive element (TMR) are used for a read element 7 of a read head 24. It is preferable that the shape of the air bearing surface of the main pole is made in a trapezoidal shape in which the width at the leading side is smaller, considering the case when the head has a skew angle. A magnetic head of the prior art consists of laminating a lower shield 8, a read element 7, an upper shield 9, an auxiliary pole 3, a thin film coil 2, and a main pole 1, in order, from the head motion side (leading side). The read head 24 is composed of the lower shield 8, the read element 7, and the upper shield 9, and the write head (single-pole-type writer) 25 is composed of the auxiliary pole 3, the thin film coil 2, and the main pole 1. The main pole 1 consists of a yoke part of main pole 1A connected to the auxiliary pole through the pillar 17 and a pole tip of main pole 1C which is exposed on the air bearing surface and determines the track width.
Moreover, since an auxiliary pole and a thin film coil exist between the read element and the main pole in the structure shown in FIG. 19, there is a disadvantage that the distance between the write element and the read element becomes greater and the format efficiency is deteriorated. Therefore, a structure, in which the auxiliary pole 3 is placed on the trailing side of the main pole 1, is to be applied as shown in FIG. 20. Because of this structure, it becomes possible to make the distance between the write element and the read element smaller.
Moreover, the magnetic field gradient of the perpendicular component profile of the head magnetic field which determines the transition of the recorded bit cell as well as the intensity of the write head magnetic field, which means the magnetic field gradient in the perpendicular component profile of the head magnetic field along the head motion, is also an important factor to achieving a high recording density. In order to achieve a higher recording density, it is necessary to make the magnetic field gradient greater in the future. There is a structure to improve the write field gradients, in which a magnetic material 32 is arranged on the trailing side of the main pole 1. In this structure, there is a case where the auxiliary pole 3 is arranged at the trailing side of the main pole 1 to make a closed magnetic circuit as shown in FIG. 20.
A magnetic head is usually fabricated by laminating a magnetic film, in order, on a substrate by using a sputtering method and a plating method. Therefore, a structure of the prior art is one in which the face of the main pole at the leading side is parallel to the substrate and perpendicular to the air bearing surface. A perpendicular recording head, in which a taper is formed at the pole tip of the main pole from the air bearing surface, is disclosed in patent document 1 (JP-A No. 133610/2002).